How can I unmap a File input without using the form builder? - symfony

Question

I have inherited an application that seems to have existed before the form builder existed. The developer kind of rolled his own with twig macros. Now I want to add a file upload to some existing forms, but I get what seems to be a well known error:
There was 1 error:
myBundle\Tests\Controller\snip\DefaultControllerUnitTest::testCanStoreDocumentAtS3
Exception: Serialization of
'Symfony\Component\HttpFoundation\File\UploadedFile' is not allowed
C:\apath\vendor\symfony\symfony\src\Symfony\Component\HttpKernel\DataCollector\DataCollector.php:27
C:\apath\vendor\symfony\symfony\src\Symfony\Component\HttpKernel\Profiler\Profiler.php:218
The solutions is to unmap the file field:
$builder->add('pic','file');
to this :
$builder->add('pic','file', array('mapped'=>false));
But in this case a builder is not used. Instead it looks like this:
{# file(name, value) #}
{% macro file(name, value) %}
<input type="file" name="{{ name }}" id="{{ name }}" value="{{ value }}" />
{% endmacro %}
Is there anything I can add to this macro, or do in the controller action to keep the Profiler from serializing this?

Answer 1

The answer was in part pilot error, but there is enough going on here that I hope I can help others avoid the same pitfall.
This error was triggered by a unit test where I was simulating a file upload along with other parameters. Initially the code that caused this error was:
$photo = new UploadedFile(
__DIR__ . '/TestReportMethod.xlsx',
'TestReportMethod.xlsx',
'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
123
);
....
$form['reportFile'] = $photo;
//submit
This caused the error in my original post.
After trying a few things I moved to this form instead.
$crawler = $this->client->request('POST',
$url,
array('id' => 328),
array('agencyInfoId' => 328),
array('reportFile' => $photo)
);
Which causes an InvalidArgumentException I think a little better example in the cookbook could have prevented. The correct form needs to be an array of parameter values, followed by an array of files:
$crawler = $this->client->request('POST',
$url,
array('id' => 328,
'agencyInfoId' => 328),
array('reportFile' => $photo)
);
I hope this helps somebody else!